B&Q, the DIY retailer, is reviewing its advertising account after five years with Engine.
The pitch is being handled directly by the brand, which is in talks with a number of agencies.
Engine, then known as WCRS, snatched the business from Karmarama in 2014. Karmarama had won the account two years earlier, after defeating WCRS in a shoot-out. Before that, advertising was handled by McCann London for three years.
Campaign understands that Engine will continue to work with B&Q in other areas. Partners Andrews Aldridge – now part of the integrated Engine – won the retailer's CRM account in 2016.
Wavemaker works on B&Q owner Kingfisher's media after the company consolidated the majority of the media account into the agency (when it was known as MEC) in 2017.
A B&Q spokeswoman said: "We have been meeting with a small number of creative agencies to identify a creative lead agency for 2020."
B&Q reported a sales decline of 2.8% to £3.4bn for the year ended 31 January 2019.
Earlier this year, B&Q rival Homebase awarded its ad account to Atomic and its media business to Havas amid a turnaround plan.
Engine directed enquiries to B&Q.